Strong Reduction in Amplitude of the Interfacial Segmental Dynamics in Polymer Nanocomposites
Résumé
Despite the wide use of polymer nanocomposites (PNCs)
in various applications, our understanding of the microscopic parameters
controlling their macroscopic properties remains limited. In this study, we
examine the dielectric strength of segmental dynamics, ΔεIL(T) in the
interfacial polymer layer surrounding the nanoparticles in PNCs. The
presented analysis reveals a significant drop in ΔεIL(T) and its anomalous
temperature dependence in the polymer layer adsorbed to nanoparticles.
The drop in ΔεIL(T) was observed in all samples regardless of whether
segmental relaxation time in the interfacial layer was slower or faster than
in the bulk polymer, excluding interpretation of the “dead” layer. We
ascribe the observed decrease in the dielectric strength to the restricted
amplitude of segmental relaxation in the interfacial/adsorbed layer. Our
results provide a new perspective on discussion of dynamics in the
interfacial layer in PNCs and thin polymer films, demonstrating that not
only segmental relaxation time but also its amplitude can be strongly affected by the interface.